This invention relates to solid electrolyte batteries and processes for producing solid electrolyte batteries. More specifically, the invention relates to solid electrolyte batteries that include a thin film-shaped all-solid electrolyte formed between a positive electrode and a negative electrode, and processes for producing such solid electrolyte batteries.
The recent rapid development of portable electronics has made portable electronic devices such as cellular phones and laptop personal computers to be recognized as the fundamental technology representing the basis of the sophisticated information society.
Further, the active research and development directed to improving the functions of these devices has lead to a proportional increase in the power consumption of the portable electronic devices. Because these electronic devices are also required to run long hours, the secondary battery, a driving power supply, is expected to have higher energy density.
Considering factors such as the occupied volume and the weight of the battery installed in portable electronic devices, the battery energy density should desirably be as high as possible. Lithium ion secondary batteries using doping and undoping of lithium ions have excellent energy density, and have been widely used in portable electronic devices.
For safety and reliability issues, the research and development of lithium ion secondary batteries are particularly active in all-solid lithium ion secondary batteries in which a solid electrolyte containing no organic electrolytic solution is used as the electrolyte. The characteristics of the solid electrolyte are very important in all-solid lithium ion secondary batteries. Accordingly, there have been active studies of inorganic solid electrolytes such as Li3PO4, and Li3VO4.
For example, X. Son et al., Journal of Materials Processing Technology 120 (2002) 21-25 describes a sintered body obtained by sintering a Li3VO4 powder. The conductivity of this sintered body is reported to be 10−8 S/cm to 10−9 S/cm at room temperature.